Video Delay When Outputting to FW DV Stream

[MIDI Life Crisis]

Never happened before, but the audio sync is out by about .5 seconds when I output to DV on a second monitor. The QT movie is spot on when the movie appear in DP. Clearly, FW is introducing a delay and while I can compensate for it, it would be nice if the sync was the same on both.

Using a Canopus AVDC-100 directly into the G5. No other artifacts to speak of. Offsetting the movie offsets the pict in DP as well, so for the moment I am offsetting the production audio (copied to DP) and with 2 pops and end pops I should be fine in terms of sync, but again, this really shouldn't be an issue and has never happened before.

Anyone else seeing this behavior? TIA.

[James Steele]

I remember reading once that there's about a 6 frame offset. I don't know if newer versions of DP let you fix it, but there was a guy on the MOTU-MAC list, Kelly Jacklin, who wrote some utility that fixed this... however he writes on his page that from DP 4.5 this isn't needed anymore. Here's his page:

http://www.jacklinstudios.com/software/dvla/" onclick="window.open(this.href);return false;

I wonder what's going on there as this is presumably fixed. I don't work much to picture, so unfortunately I don't have anything better to tell you.

Even though DP isn't supposed to be doing this, you might be able to press his utility into fixing the issue for now until you figure out what's going on here.

[MIDI Life Crisis]

Thanks James. It may be a FW issue as well. I'm not so quick to place the blame on DP since the sync is correct when the movie is not being output to FW. I'm hesitant to run a program to "fix it" until I figure out what is actually going on. When I have a few minutes to spare I'll call MOTu or start a techlink. Still a few troubleshooting ideas to kick around as well.

I should also mention (come to think of it...) that I am running the FW into a Mac Mini via EyeTV which may well be the culprit. I'll try a direct line into a monitor but as i write this, I am thinking EyeTV may well be the cause of the delay. In the past, I ran directly to the monitor and this is the first time I am outputting the DV Stream to EyeTV in a critical project.

More as I troubleshoot this. If it is EyeTV then others may find the thread useful in the future (and of course, I'll change the title to make that easier to find.)

Thanks for the response and the link. I'll take a peek shortly to see what Kelly had to say about it.

[stephentayler]

From my experience, DV output always introduces a delay of around 8 frames..... so I don't think you can use the DP offset to correct this AND have the movie in sync on the Mac window simultaneously.... this is also true for Final Cut

Cheers

Stephen

[James Steele]

I should also mention (come to think of it...) that I am running the FW into a Mac Mini via EyeTV which may well be the culprit. I'll try a direct line into a monitor but as i write this, I am thinking EyeTV may well be the cause of the delay. In the past, I ran directly to the monitor and this is the first time I am outputting the DV Stream to EyeTV in a critical project.

I'll betcha that's it. As far as Kelly's utility... not sure what OS it was intended for so may not want to do that. Although I can tell you that OS changes at Apple notwithstanding, it was probably a find utility. Kelly's day gig is programming for a larger technology company based in Cupertino, California.

[MIDI Life Crisis]

I double betcha you're right! More as data becomes available.

[martian]

it's true that the DP QT playback offset is added to both the echo"d video as well as DV output -

there's no way around that offset either as its part of the DV codec - i found that it changes a bit from device to device- I use a sony DVcam and its 8 frames! whilst in a DV converter box it's just 5...

Actually before ( which version of DP 4? forgot!! ) there was no DV offset - and I used to fudge it using Buffy,,,

maybe that could help ? - stick a buffy on the outs which feed the mons in the room using the DV box ?

( I must admit it was the lack of dv offset which sent me scuttling to LE land for a while - but track counts and bounce times put me right off and by 4.61 it was solved?..)

[dp-user]

DP does DV latency correction (which is what my old DVLA component used to do). Basically, it sends frames to the DV data handler 7 frames (or whatever, you set the number) early during playback, so that they appear on the external monitor and on the screen at the same time (and in sync with the audio playback). This has been a feature of DP since DP 5 (or so). it is documented in the manual.

[MIDI Life Crisis]

... and it's worked like that until now so it must be EyeTV. No time to mess with it yet.

[ScottGlasgow]

I have also seen extra delays caused by certain video cards that the QT is on. For instance- in my MacPro I have a ATI Radeon HD 2600XT and a NVIDIA GeForce GT 120. When the QT video is on the ATI it slows down more than the NVIDIA. I mean the little QT window in DP that is going out the firewire.

Just by moving the little host QT window in DP to a different screen the video has better sync. Strange but true.